PipC affects the virulence of serovar and its deletion strain provides effective immune protection in mice.

BACKGROUND

Salmonellosis caused by sp. is a foodborne zoonotic disease that poses a significant threat to public health security. Vaccination is a safe and effective strategy for preventing and controlling infections. PipC is a chaperone protein associated with invasion proteins which is crucial for bacteria to invade host cells.

METHODS

In this study, a Δ mutant strain was generated. Subsequently, we examined the environmental stress tolerance of the mutant strain through simulation experiments. Moreover, its virulence by employing cell and mouse infection models was investigated. Furthermore, we utilized a mouse model to further explore its potential as an attenuated live vaccine against serovar infection.

RESULTS

The strain C50336 with a deletion of the gene exhibits a significant reduction in its ability to resist environmental stress and virulence. Meanwhile, the expression levels of SPI-1-related genes (, , , , , and ) and SPI-2-related genes (, , , , , , , and ) encoding the type III secretion system (T3SS) were found to be decreased, leading to a significant reduction in the bacteria's invasion and intracellular survival abilities. The results of the mouse intraperitoneal challenge experiment showed that compared with the wild-type strain, the 50% lethal dose (LD) of the Δ strain increased by 47 times, and the bacterial loads in the liver, spleen, and cecum were significantly reduced. When mice were immunized with the Δ mutant strain, the immunized mice showed a robust immune response, with significantly increased cytokine and antibody levels in their bodies. Mice vaccinated with the Δ mutant strain had 100% immune protection against wild-type infection.

CONCLUSION

This study demonstrates that lack of affects pathogenicity by decreasing its virulence both and . Vaccination of mice with Δ conferred development of an acquired immunity and efficacious protection against experimental systemic infection. These results indicated that the Δ mutant strain can be used in the development of attenuated live vaccines.